On Scientists v. Politicians on Mammograms

November 24th 2009

Elvin Lim is Assistant Professor of Government at Wesleyan University and author of The Anti-intellectual Presidency, which draws on interviews with more than 40 presidential speechwriters to investigate this relentless qualitative decline, over the course of 200 years, in our presidents’ ability to communicate with the public. He also blogs at www.elvinlim.com. In the article below, he looks at the new recommendation that women only undergo routine mammograms after the age of 50. See Lim’s previous OUPblogs here.

Last week, the United States Preventive Services Task Force, a government-appointed group of 16 outside experts recommended that women should undergo routine mammograms only after the age of 50 and not 40, against the advice of the American Cancer Society and consistent with the recommendations of the American College of Physicians.

Medicine is not a precise science, so the task force could be right but it could also be wrong. Researchers and scientists make probabilistic claims from the data to offer recommendations, in this case, to the Department of Health and Human Services.

To prevent one additional breast cancer death, 1,000 women would have to get mammograms starting at age 40 rather than 50. But doing this would allegedly result in roughly 500 of the 1,000 women getting false positive results at least once, and 33 of them getting unnecessary biopsies, according to Jeanne Mandelblatt of Georgetown University.

According to researchers on the side of the Task Force, the adage that prevention is better than cure loses its intuitive force when one scrutinizes the risks associated with preventive care such as radiation or hormone therapy on abnormalities that may never have become cancerous tumors as well as the anxiety they provoke.

Now, other experts looking at the same data disagree on its interpretation. “We respect the task force, but we do not agree with their conclusions,” says Leonard Lichtenfeld, deputy chief medical officer of the American Cancer Society. “We are concerned the same evidence we think supports beginning at age 40 is being interpreted by others as not supporting mammography.”

Scientists looking at the evidence can disagree, but when they do, they point to the data in order to support their conclusions. Most politicians, on the other hand, do not look at the data and they can in good faith either accept or reject the experts’ recommendations since the experts do disagree. Only a few, however, grab one set of these recommendations, and then leap a few light years ahead, with uncanny certitude, to a conclusion solar systems away from the data on which the recommendations were originally offered.

“This is how rationing begins. This is the little toe in the edge of the water,” Rep. Marsha Blackburn (R-TN) said Wednesday on Capitol Hill. “This is when you start getting a bureaucrat between you and your physician.”

This is when you put a politician between the people and responsible government. They will offer answers, explanations, and analogies with more certititude than the scientists who perused the data, and if their golden tongues wagged with enough vigor, people will believe them because it is easier to acquire information via gossip than it is to collect it ourselves.

Our indifference to doing our civic homework would not be a problem but for the fact that demagogues are able to synthesize our indifference with their certainty to create political slogans but not political solutions. Resolution and confidence are virtues only when the answers are always obvious and unambiguous. But in the world of statistics in which researchers on both sides of the mammogram debate inhabit, and in the world of politics where the meaning of public opinion and the general will fluctuates, unsubstantiated certitude is the one cancer on democacy we should be screening for, every day.